Support HTTP caching of app.js

7 files changed, 266 insertions, 61 deletions

diff --git a/.hgignore b/.hgignore
index cd7886cd..03daa61a 100644
--- a/.hgignore
+++ b/.hgignore
@@ -53,3 +53,6 @@ syntax: regexp
 ^src/c/Makefile$
 ^src/coq/Makefile$
 ^libtool$
+^config.h$
+^config.h.in$
+^stamp-h1$
diff --git a/Makefile.am b/Makefile.am
index 81436cea..9de5f6c6 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -68,6 +68,7 @@ install-exec-local:
 	mkdir -p $(LIB_JS)
 	cp lib/js/*.js $(LIB_JS)/
 	mkdir -p $(INCLUDE)
+	cp config.h $(INCLUDE)/
 	cp include/*.h $(INCLUDE)/
 	mkdir -p $(SITELISP)
 	cp src/elisp/*.el $(SITELISP)/
diff --git a/Makefile.in b/Makefile.in
index 67263703..8ccf42fc 100644
--- a/Makefile.in
+++ b/Makefile.in
@@ -35,9 +35,9 @@ build_triplet = @build@
 host_triplet = @host@
 subdir = .
 DIST_COMMON = $(am__configure_deps) $(srcdir)/Makefile.am \
-	$(srcdir)/Makefile.in $(top_srcdir)/configure \
-	$(top_srcdir)/src/config.sml.in config.guess config.sub \
-	depcomp install-sh ltmain.sh missing
+	$(srcdir)/Makefile.in $(srcdir)/config.h.in \
+	$(top_srcdir)/configure $(top_srcdir)/src/config.sml.in \
+	config.guess config.sub depcomp install-sh ltmain.sh missing
 ACLOCAL_M4 = $(top_srcdir)/aclocal.m4
 am__aclocal_m4_deps = $(top_srcdir)/m4/libtool.m4 \
 	$(top_srcdir)/m4/ltoptions.m4 $(top_srcdir)/m4/ltsugar.m4 \
@@ -48,6 +48,7 @@ am__configure_deps = $(am__aclocal_m4_deps) $(CONFIGURE_DEPENDENCIES) \
 am__CONFIG_DISTCLEAN_FILES = config.status config.cache config.log \
  configure.lineno config.status.lineno
 mkinstalldirs = $(install_sh) -d
+CONFIG_HEADER = config.h
 CONFIG_CLEAN_FILES = src/config.sml
 CONFIG_CLEAN_VPATH_FILES =
 SOURCES =
@@ -227,7 +228,8 @@ LIB_UR := $(LIB)/ur
 LIB_C := $(LIB)/c
 LIB_JS := $(LIB)/js
 SUBDIRS = src/c
-all: all-recursive
+all: config.h
+	$(MAKE) $(AM_MAKEFLAGS) all-recursive
 
 .SUFFIXES:
 am--refresh:
@@ -264,6 +266,23 @@ $(top_srcdir)/configure:  $(am__configure_deps)
 $(ACLOCAL_M4):  $(am__aclocal_m4_deps)
 	$(am__cd) $(srcdir) && $(ACLOCAL) $(ACLOCAL_AMFLAGS)
 $(am__aclocal_m4_deps):
+
+config.h: stamp-h1
+	@if test ! -f $@; then \
+	  rm -f stamp-h1; \
+	  $(MAKE) $(AM_MAKEFLAGS) stamp-h1; \
+	else :; fi
+
+stamp-h1: $(srcdir)/config.h.in $(top_builddir)/config.status
+	@rm -f stamp-h1
+	cd $(top_builddir) && $(SHELL) ./config.status config.h
+$(srcdir)/config.h.in:  $(am__configure_deps) 
+	($(am__cd) $(top_srcdir) && $(AUTOHEADER))
+	rm -f stamp-h1
+	touch $@
+
+distclean-hdr:
+	-rm -f config.h stamp-h1
 src/config.sml: $(top_builddir)/config.status $(top_srcdir)/src/config.sml.in
 	cd $(top_builddir) && $(SHELL) ./config.status $@
 
@@ -356,7 +375,7 @@ ID: $(HEADERS) $(SOURCES) $(LISP) $(TAGS_FILES)
 	mkid -fID $$unique
 tags: TAGS
 
-TAGS: tags-recursive $(HEADERS) $(SOURCES)  $(TAGS_DEPENDENCIES) \
+TAGS: tags-recursive $(HEADERS) $(SOURCES) config.h.in $(TAGS_DEPENDENCIES) \
 		$(TAGS_FILES) $(LISP)
 	set x; \
 	here=`pwd`; \
@@ -373,7 +392,7 @@ TAGS: tags-recursive $(HEADERS) $(SOURCES)  $(TAGS_DEPENDENCIES) \
 	      set "$$@" "$$include_option=$$here/$$subdir/TAGS"; \
 	  fi; \
 	done; \
-	list='$(SOURCES) $(HEADERS)  $(LISP) $(TAGS_FILES)'; \
+	list='$(SOURCES) $(HEADERS) config.h.in $(LISP) $(TAGS_FILES)'; \
 	unique=`for i in $$list; do \
 	    if test -f "$$i"; then echo $$i; else echo $(srcdir)/$$i; fi; \
 	  done | \
@@ -391,9 +410,9 @@ TAGS: tags-recursive $(HEADERS) $(SOURCES)  $(TAGS_DEPENDENCIES) \
 	  fi; \
 	fi
 ctags: CTAGS
-CTAGS: ctags-recursive $(HEADERS) $(SOURCES)  $(TAGS_DEPENDENCIES) \
+CTAGS: ctags-recursive $(HEADERS) $(SOURCES) config.h.in $(TAGS_DEPENDENCIES) \
 		$(TAGS_FILES) $(LISP)
-	list='$(SOURCES) $(HEADERS)  $(LISP) $(TAGS_FILES)'; \
+	list='$(SOURCES) $(HEADERS) config.h.in $(LISP) $(TAGS_FILES)'; \
 	unique=`for i in $$list; do \
 	    if test -f "$$i"; then echo $$i; else echo $(srcdir)/$$i; fi; \
 	  done | \
@@ -588,7 +607,7 @@ distcleancheck: distclean
 	       exit 1; } >&2
 check-am: all-am
 check: check-recursive
-all-am: Makefile all-local
+all-am: Makefile config.h all-local
 installdirs: installdirs-recursive
 installdirs-am:
 install: install-recursive
@@ -623,8 +642,8 @@ clean-am: clean-generic clean-libtool clean-local mostlyclean-am
 distclean: distclean-recursive
 	-rm -f $(am__CONFIG_DISTCLEAN_FILES)
 	-rm -f Makefile
-distclean-am: clean-am distclean-generic distclean-libtool \
-	distclean-tags
+distclean-am: clean-am distclean-generic distclean-hdr \
+	distclean-libtool distclean-tags
 
 dvi: dvi-recursive
 
@@ -686,19 +705,19 @@ ps-am:
 
 uninstall-am:
 
-.MAKE: $(RECURSIVE_CLEAN_TARGETS) $(RECURSIVE_TARGETS) ctags-recursive \
-	install-am install-strip tags-recursive
+.MAKE: $(RECURSIVE_CLEAN_TARGETS) $(RECURSIVE_TARGETS) all \
+	ctags-recursive install-am install-strip tags-recursive
 
 .PHONY: $(RECURSIVE_CLEAN_TARGETS) $(RECURSIVE_TARGETS) CTAGS GTAGS \
 	all all-am all-local am--refresh check check-am clean \
 	clean-generic clean-libtool clean-local ctags ctags-recursive \
 	dist dist-all dist-bzip2 dist-gzip dist-lzma dist-shar \
 	dist-tarZ dist-xz dist-zip distcheck distclean \
-	distclean-generic distclean-libtool distclean-tags \
-	distcleancheck distdir distuninstallcheck dvi dvi-am html \
-	html-am info info-am install install-am install-data \
-	install-data-am install-dvi install-dvi-am install-exec \
-	install-exec-am install-exec-local install-html \
+	distclean-generic distclean-hdr distclean-libtool \
+	distclean-tags distcleancheck distdir distuninstallcheck dvi \
+	dvi-am html html-am info info-am install install-am \
+	install-data install-data-am install-dvi install-dvi-am \
+	install-exec install-exec-am install-exec-local install-html \
 	install-html-am install-info install-info-am install-man \
 	install-pdf install-pdf-am install-ps install-ps-am \
 	install-strip installcheck installcheck-am installdirs \
@@ -762,6 +781,7 @@ install-exec-local:
 	mkdir -p $(LIB_JS)
 	cp lib/js/*.js $(LIB_JS)/
 	mkdir -p $(INCLUDE)
+	cp config.h $(INCLUDE)/
 	cp include/*.h $(INCLUDE)/
 	mkdir -p $(SITELISP)
 	cp src/elisp/*.el $(SITELISP)/
diff --git a/configure b/configure
index 317e8f5c..725d8656 100755
--- a/configure
+++ b/configure
@@ -11000,6 +11000,8 @@ CC="$lt_save_CC"
 
 
 
+ac_config_headers="$ac_config_headers config.h"
+
 
 { $as_echo "$as_me:${as_lineno-$LINENO}: checking for mhash_get_block_size in -lmhash" >&5
 $as_echo_n "checking for mhash_get_block_size in -lmhash... " >&6; }
@@ -11294,43 +11296,7 @@ test "x$prefix" = xNONE && prefix=$ac_default_prefix
 # Let make expand exec_prefix.
 test "x$exec_prefix" = xNONE && exec_prefix='${prefix}'
 
-# Transform confdefs.h into DEFS.
-# Protect against shell expansion while executing Makefile rules.
-# Protect against Makefile macro expansion.
-#
-# If the first sed substitution is executed (which looks for macros that
-# take arguments), then branch to the quote section.  Otherwise,
-# look for a macro that doesn't take arguments.
-ac_script='
-:mline
-/\\$/{
- N
- s,\\\n,,
- b mline
-}
-t clear
-:clear
-s/^[	 ]*#[	 ]*define[	 ][	 ]*\([^	 (][^	 (]*([^)]*)\)[	 ]*\(.*\)/-D\1=\2/g
-t quote
-s/^[	 ]*#[	 ]*define[	 ][	 ]*\([^	 ][^	 ]*\)[	 ]*\(.*\)/-D\1=\2/g
-t quote
-b any
-:quote
-s/[	 `~#$^&*(){}\\|;'\''"<>?]/\\&/g
-s/\[/\\&/g
-s/\]/\\&/g
-s/\$/$$/g
-H
-:any
-${
-	g
-	s/^\n//
-	s/\n/ /g
-	p
-}
-'
-DEFS=`sed -n "$ac_script" confdefs.h`
-
+DEFS=-DHAVE_CONFIG_H
 
 ac_libobjs=
 ac_ltlibobjs=
@@ -11790,11 +11756,15 @@ case $ac_config_files in *"
 "*) set x $ac_config_files; shift; ac_config_files=$*;;
 esac
 
+case $ac_config_headers in *"
+"*) set x $ac_config_headers; shift; ac_config_headers=$*;;
+esac
 
 
 cat >>$CONFIG_STATUS <<_ACEOF || ac_write_fail=1
 # Files that config.status was made for.
 config_files="$ac_config_files"
+config_headers="$ac_config_headers"
 config_commands="$ac_config_commands"
 
 _ACEOF
@@ -11816,10 +11786,15 @@ Usage: $0 [OPTION]... [TAG]...
       --recheck    update $as_me by reconfiguring in the same conditions
       --file=FILE[:TEMPLATE]
                    instantiate the configuration file FILE
+      --header=FILE[:TEMPLATE]
+                   instantiate the configuration header FILE
 
 Configuration files:
 $config_files
 
+Configuration headers:
+$config_headers
+
 Configuration commands:
 $config_commands
 
@@ -11880,7 +11855,18 @@ do
     esac
     as_fn_append CONFIG_FILES " '$ac_optarg'"
     ac_need_defaults=false;;
-  --he | --h |  --help | --hel | -h )
+  --header | --heade | --head | --hea )
+    $ac_shift
+    case $ac_optarg in
+    *\'*) ac_optarg=`$as_echo "$ac_optarg" | sed "s/'/'\\\\\\\\''/g"` ;;
+    esac
+    as_fn_append CONFIG_HEADERS " '$ac_optarg'"
+    ac_need_defaults=false;;
+  --he | --h)
+    # Conflict between --help and --header
+    as_fn_error "ambiguous option: \`$1'
+Try \`$0 --help' for more information.";;
+  --help | --hel | -h )
     $as_echo "$ac_cs_usage"; exit ;;
   -q | -quiet | --quiet | --quie | --qui | --qu | --q \
   | -silent | --silent | --silen | --sile | --sil | --si | --s)
@@ -12198,6 +12184,7 @@ do
   case $ac_config_target in
     "depfiles") CONFIG_COMMANDS="$CONFIG_COMMANDS depfiles" ;;
     "libtool") CONFIG_COMMANDS="$CONFIG_COMMANDS libtool" ;;
+    "config.h") CONFIG_HEADERS="$CONFIG_HEADERS config.h" ;;
     "Makefile") CONFIG_FILES="$CONFIG_FILES Makefile" ;;
     "src/c/Makefile") CONFIG_FILES="$CONFIG_FILES src/c/Makefile" ;;
     "src/config.sml") CONFIG_FILES="$CONFIG_FILES src/config.sml" ;;
@@ -12213,6 +12200,7 @@ done
 # bizarre bug on SunOS 4.1.3.
 if $ac_need_defaults; then
   test "${CONFIG_FILES+set}" = set || CONFIG_FILES=$config_files
+  test "${CONFIG_HEADERS+set}" = set || CONFIG_HEADERS=$config_headers
   test "${CONFIG_COMMANDS+set}" = set || CONFIG_COMMANDS=$config_commands
 fi
 
@@ -12391,8 +12379,116 @@ fi
 cat >>$CONFIG_STATUS <<\_ACEOF || ac_write_fail=1
 fi # test -n "$CONFIG_FILES"
 
+# Set up the scripts for CONFIG_HEADERS section.
+# No need to generate them if there are no CONFIG_HEADERS.
+# This happens for instance with `./config.status Makefile'.
+if test -n "$CONFIG_HEADERS"; then
+cat >"$tmp/defines.awk" <<\_ACAWK ||
+BEGIN {
+_ACEOF
+
+# Transform confdefs.h into an awk script `defines.awk', embedded as
+# here-document in config.status, that substitutes the proper values into
+# config.h.in to produce config.h.
+
+# Create a delimiter string that does not exist in confdefs.h, to ease
+# handling of long lines.
+ac_delim='%!_!# '
+for ac_last_try in false false :; do
+  ac_t=`sed -n "/$ac_delim/p" confdefs.h`
+  if test -z "$ac_t"; then
+    break
+  elif $ac_last_try; then
+    as_fn_error "could not make $CONFIG_HEADERS" "$LINENO" 5
+  else
+    ac_delim="$ac_delim!$ac_delim _$ac_delim!! "
+  fi
+done
+
+# For the awk script, D is an array of macro values keyed by name,
+# likewise P contains macro parameters if any.  Preserve backslash
+# newline sequences.
+
+ac_word_re=[_$as_cr_Letters][_$as_cr_alnum]*
+sed -n '
+s/.\{148\}/&'"$ac_delim"'/g
+t rset
+:rset
+s/^[	 ]*#[	 ]*define[	 ][	 ]*/ /
+t def
+d
+:def
+s/\\$//
+t bsnl
+s/["\\]/\\&/g
+s/^ \('"$ac_word_re"'\)\(([^()]*)\)[	 ]*\(.*\)/P["\1"]="\2"\
+D["\1"]=" \3"/p
+s/^ \('"$ac_word_re"'\)[	 ]*\(.*\)/D["\1"]=" \2"/p
+d
+:bsnl
+s/["\\]/\\&/g
+s/^ \('"$ac_word_re"'\)\(([^()]*)\)[	 ]*\(.*\)/P["\1"]="\2"\
+D["\1"]=" \3\\\\\\n"\\/p
+t cont
+s/^ \('"$ac_word_re"'\)[	 ]*\(.*\)/D["\1"]=" \2\\\\\\n"\\/p
+t cont
+d
+:cont
+n
+s/.\{148\}/&'"$ac_delim"'/g
+t clear
+:clear
+s/\\$//
+t bsnlc
+s/["\\]/\\&/g; s/^/"/; s/$/"/p
+d
+:bsnlc
+s/["\\]/\\&/g; s/^/"/; s/$/\\\\\\n"\\/p
+b cont
+' <confdefs.h | sed '
+s/'"$ac_delim"'/"\\\
+"/g' >>$CONFIG_STATUS || ac_write_fail=1
+
+cat >>$CONFIG_STATUS <<_ACEOF || ac_write_fail=1
+  for (key in D) D_is_set[key] = 1
+  FS = ""
+}
+/^[\t ]*#[\t ]*(define|undef)[\t ]+$ac_word_re([\t (]|\$)/ {
+  line = \$ 0
+  split(line, arg, " ")
+  if (arg[1] == "#") {
+    defundef = arg[2]
+    mac1 = arg[3]
+  } else {
+    defundef = substr(arg[1], 2)
+    mac1 = arg[2]
+  }
+  split(mac1, mac2, "(") #)
+  macro = mac2[1]
+  prefix = substr(line, 1, index(line, defundef) - 1)
+  if (D_is_set[macro]) {
+    # Preserve the white space surrounding the "#".
+    print prefix "define", macro P[macro] D[macro]
+    next
+  } else {
+    # Replace #undef with comments.  This is necessary, for example,
+    # in the case of _POSIX_SOURCE, which is predefined and required
+    # on some systems where configure will not decide to define it.
+    if (defundef == "undef") {
+      print "/*", prefix defundef, macro, "*/"
+      next
+    }
+  }
+}
+{ print }
+_ACAWK
+_ACEOF
+cat >>$CONFIG_STATUS <<\_ACEOF || ac_write_fail=1
+  as_fn_error "could not setup config headers machinery" "$LINENO" 5
+fi # test -n "$CONFIG_HEADERS"
+
 
-eval set X "  :F $CONFIG_FILES      :C $CONFIG_COMMANDS"
+eval set X "  :F $CONFIG_FILES  :H $CONFIG_HEADERS    :C $CONFIG_COMMANDS"
 shift
 for ac_tag
 do
@@ -12610,7 +12706,64 @@ which seems to be undefined.  Please make sure it is defined." >&2;}
   esac \
   || as_fn_error "could not create $ac_file" "$LINENO" 5
  ;;
-
+  :H)
+  #
+  # CONFIG_HEADER
+  #
+  if test x"$ac_file" != x-; then
+    {
+      $as_echo "/* $configure_input  */" \
+      && eval '$AWK -f "$tmp/defines.awk"' "$ac_file_inputs"
+    } >"$tmp/config.h" \
+      || as_fn_error "could not create $ac_file" "$LINENO" 5
+    if diff "$ac_file" "$tmp/config.h" >/dev/null 2>&1; then
+      { $as_echo "$as_me:${as_lineno-$LINENO}: $ac_file is unchanged" >&5
+$as_echo "$as_me: $ac_file is unchanged" >&6;}
+    else
+      rm -f "$ac_file"
+      mv "$tmp/config.h" "$ac_file" \
+	|| as_fn_error "could not create $ac_file" "$LINENO" 5
+    fi
+  else
+    $as_echo "/* $configure_input  */" \
+      && eval '$AWK -f "$tmp/defines.awk"' "$ac_file_inputs" \
+      || as_fn_error "could not create -" "$LINENO" 5
+  fi
+# Compute "$ac_file"'s index in $config_headers.
+_am_arg="$ac_file"
+_am_stamp_count=1
+for _am_header in $config_headers :; do
+  case $_am_header in
+    $_am_arg | $_am_arg:* )
+      break ;;
+    * )
+      _am_stamp_count=`expr $_am_stamp_count + 1` ;;
+  esac
+done
+echo "timestamp for $_am_arg" >`$as_dirname -- "$_am_arg" ||
+$as_expr X"$_am_arg" : 'X\(.*[^/]\)//*[^/][^/]*/*$' \| \
+	 X"$_am_arg" : 'X\(//\)[^/]' \| \
+	 X"$_am_arg" : 'X\(//\)$' \| \
+	 X"$_am_arg" : 'X\(/\)' \| . 2>/dev/null ||
+$as_echo X"$_am_arg" |
+    sed '/^X\(.*[^/]\)\/\/*[^/][^/]*\/*$/{
+	    s//\1/
+	    q
+	  }
+	  /^X\(\/\/\)[^/].*/{
+	    s//\1/
+	    q
+	  }
+	  /^X\(\/\/\)$/{
+	    s//\1/
+	    q
+	  }
+	  /^X\(\/\).*/{
+	    s//\1/
+	    q
+	  }
+	  s/.*/./; q'`/stamp-h$_am_stamp_count
+ ;;
 
   :C)  { $as_echo "$as_me:${as_lineno-$LINENO}: executing $ac_file commands" >&5
 $as_echo "$as_me: executing $ac_file commands" >&6;}
diff --git a/configure.ac b/configure.ac
index d65d6e4c..9b7c02a9 100644
--- a/configure.ac
+++ b/configure.ac
@@ -4,6 +4,7 @@ AM_INIT_AUTOMAKE([-Wall -Werror foreign no-define])
 AC_PROG_CC()
 AC_PROG_LIBTOOL()
 AC_CONFIG_MACRO_DIR([m4])
+AC_CONFIG_HEADERS([config.h])
 
 AC_CHECK_LIB(mhash, mhash_get_block_size, [], [echo "You must install libmhash."; exit 1])
 AC_CHECK_HEADER([mhash.h], [], [echo "You must install libmhash dev files."; exit 1])
diff --git a/src/c/Makefile.in b/src/c/Makefile.in
index 98f431f9..59d7b3e4 100644
--- a/src/c/Makefile.in
+++ b/src/c/Makefile.in
@@ -44,6 +44,7 @@ am__aclocal_m4_deps = $(top_srcdir)/m4/libtool.m4 \
 am__configure_deps = $(am__aclocal_m4_deps) $(CONFIGURE_DEPENDENCIES) \
 	$(ACLOCAL_M4)
 mkinstalldirs = $(install_sh) -d
+CONFIG_HEADER = $(top_builddir)/config.h
 CONFIG_CLEAN_FILES =
 CONFIG_CLEAN_VPATH_FILES =
 am__vpath_adj_setup = srcdirstrip=`echo "$(srcdir)" | sed 's|.|.|g'`;
@@ -82,7 +83,7 @@ liburweb_fastcgi_la_OBJECTS = $(am_liburweb_fastcgi_la_OBJECTS)
 liburweb_http_la_LIBADD =
 am_liburweb_http_la_OBJECTS = http.lo
 liburweb_http_la_OBJECTS = $(am_liburweb_http_la_OBJECTS)
-DEFAULT_INCLUDES = -I.@am__isrc@
+DEFAULT_INCLUDES = -I.@am__isrc@ -I$(top_builddir)
 depcomp = $(SHELL) $(top_srcdir)/depcomp
 am__depfiles_maybe = depfiles
 am__mv = mv -f
diff --git a/src/cjr_print.sml b/src/cjr_print.sml
index 06999dec..34936aac 100644
--- a/src/cjr_print.sml
+++ b/src/cjr_print.sml
@@ -2780,8 +2780,17 @@ fun p_file env (ds, ps) =
                  newline]
 
         val initializers = List.mapPartial (fn (DTask (Initialize, e), _) => SOME e | _ => NONE) ds
+
+        val now = Time.now ()
+        val nowD = Date.fromTimeUniv now
+        val rfcFmt = "%a, %d %b %Y %H:%M:%S"
     in
-        box [string "#include <stdio.h>",
+        box [string "#include \"",
+             string (OS.Path.joinDirFile {dir = Config.includ,
+                                          file = "config.h"}),
+             string "\"",
+             newline,
+             string "#include <stdio.h>",
              newline,
              string "#include <stdlib.h>",
              newline,
@@ -2789,6 +2798,8 @@ fun p_file env (ds, ps) =
              newline,
              string "#include <math.h>",
              newline,
+             string "#include <time.h>",
+             newline,
              if hasDb then
                  box [string ("#include <" ^ #header (Settings.currentDbms ()) ^ ">"),
                       newline]
@@ -2875,7 +2886,22 @@ fun p_file env (ds, ps) =
                                           file = "app.js"}),
              string "\")) {",
              newline,
-             box [string "uw_write_header(ctx, \"Content-type: text/javascript\\r\\n\");",
+             box [string "uw_Basis_string ims = uw_Basis_requestHeader(ctx, \"If-modified-since\");",
+                  newline,
+                  string ("if (ims && !strcmp(ims, \"" ^ Date.fmt rfcFmt nowD ^ "\")) {"),
+                  newline,
+                  box [string "uw_clear_headers(ctx);",
+                       newline,
+                       string "uw_write_header(ctx, \"HTTP/1.1 304 Not Modified\\r\\n\");",
+                       newline,
+                       string "return;",
+                       newline],
+                  string "}",
+                  newline,
+                  newline,
+                  string "uw_write_header(ctx, \"Content-type: text/javascript\\r\\n\");",
+                  newline,
+                  string ("uw_write_header(ctx, \"Last-modified: " ^ Date.fmt rfcFmt nowD ^ "\\r\\n\");"),
                   newline,
                   string "uw_write(ctx, jslib);",
                   newline,